No, a QR code is not required when using SIGN IT lite.
Displaying a QR code is only mandatory if you are using a physical fiscal cash register (Registratore Telematico – RT).
When using SIGN IT lite, receipts are generated directly through the AdE's online portal using the "Documento commerciale online" web procedure. This ensures that transaction data is transmitted immediately and securely to the tax authorities.
The fiscal validity and compliance of the receipt are guaranteed by its digital creation and registration within the AdE systems.
For guidance on how merchants should proceed during an audit, see this article: SIGN IT - How to handle an audit with SIGN IT lite?